Electronic apparatus now often have displays. However, it is not always possible to display in such a display all the information that a user may wish to view. In such circumstances, it may be necessary to define different output states that have different corresponding information and to provide the user with a way of navigating from one output state to another.
For example, in Microsoft Windows, running applications have an icon in the Windows taskbar. Selecting the icon for an application makes that application the current active application. The output state changes and a screen for the selected application is displayed in front of the screens for the other applications.